compress.c
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上传日期:2007-01-04
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文件大小:2k
- /* compress.c -- compress a memory buffer
- * Copyright (C) 1995 Jean-loup Gailly.
- * For conditions of distribution and use, see copyright notice in zlib.h
- */
- /* $Id: compress.c,v 1.6 1995/05/03 17:27:08 jloup Exp $ */
- #include "zlib.h"
- /* ===========================================================================
- Compresses the source buffer into the destination buffer. sourceLen is
- the byte length of the source buffer. Upon entry, destLen is the total
- size of the destination buffer, which must be at least 0.1% larger than
- sourceLen plus 8 bytes. Upon exit, destLen is the actual size of the
- compressed buffer.
- This function can be used to compress a whole file at once if the
- input file is mmap'ed.
- compress returns Z_OK if success, Z_MEM_ERROR if there was not
- enough memory, Z_BUF_ERROR if there was not enough room in the output
- buffer.
- */
- int compress (dest, destLen, source, sourceLen)
- Bytef *dest;
- uLongf *destLen;
- Bytef *source;
- uLong sourceLen;
- {
- z_stream stream;
- int err;
- stream.next_in = source;
- stream.avail_in = (uInt)sourceLen;
- /* Check for source > 64K on 16-bit machine: */
- if ((uLong)stream.avail_in != sourceLen) return Z_BUF_ERROR;
- stream.next_out = dest;
- stream.avail_out = (uInt)*destLen;
- if ((uLong)stream.avail_out != *destLen) return Z_BUF_ERROR;
- stream.zalloc = (alloc_func)0;
- stream.zfree = (free_func)0;
- err = deflateInit(&stream, Z_DEFAULT_COMPRESSION);
- if (err != Z_OK) return err;
- err = deflate(&stream, Z_FINISH);
- if (err != Z_STREAM_END) {
- deflateEnd(&stream);
- return err == Z_OK ? Z_BUF_ERROR : err;
- }
- *destLen = stream.total_out;
- err = deflateEnd(&stream);
- return err;
- }